Long skeletal structures and especially large weight supporting bones, e.g., tibia, femur, humerus and radius, when fractured often require the introduction of a rod-like device into the medullary canal as a supporting structure and means for repairing the fracture. Current orthopedic practice calls for the introduction of the metal rod or intramedullary device down through the canal of the broken bone to aid in holding the fractured portions together. The rod must then be secured to the bone using either a pin, a nail, bolt or screw, to prevent slippage in the medullary canal when under stress. This is usually carried out first by forming a continuous channel consisting of a predrilled transverse hole in the distal end of the rod and through adjacent corticals of the injured bone. Through such a continuous channel a pin is introduced to affix the rod to the bone.
However, most processes for fixation of the rod require the surgeon to drill "blindly" into the bone from the outside wall in an effort to locate the predrilled hole in the rod. The process of drilling holes in bone which are aligned with the predrilled holes in the rod is inexact, and often performed on a trial and error basis. Consequently, the fixation of an intramedullary device can be and often is a tedious and time consuming process. This also translates into protracted operating room times, added risk to the patient due to longer anesthesia times, risk of further tissue damage, external scarring and increased radiation exposure to the patient and providers.
Various alternative methods for fixation of intramedullary rods have been proposed in an effort to overcome the foregoing problems. For example, fluoroscopy has been used by surgeons for visualization of the predrilled holes in the rod for more accurate drilling of bone. However, fluoroscopy provides only two dimensional images of a three dimensional target, and consequently, the predrilled holes in the rod under the bone are often not visible. Fluoroscopy also means added cost both for the equipment in the operating room and for staffing with an x-ray technician. Laser guidance, plus fluoroscopy, while providing some improvement over fluoroscopy alone, still does not provide consistently reliable images. Other methods have relied on external clamps and drill guides, for example. They too have limitations, including interference by anatomic variations, and less than ideal positioning of the rod in the bone canal making them cumbersome to use.
A further process disclosed by U.S. Pat. No. 4,781,181 to Tanguy provides for positioning an intramedullary rod in the canal of a fractured bone, and with the aid of a boring sensor comprising a translatable drill guiding and positioning unit, a drill bit on a flexible shaft is inserted into the rod interior beginning at the proximal end of the intramedullary rod for drilling a hole from the inside of the bone adjacent to the predrilled opening in the distal end of the rod. While this assures alignment of the predrilled holes in the rod with the holes drilled in the bone for insertion of a pin, before the drill bit can be inserted the boring sensor must be inserted into the rod interior and locked into place at the distal end where it is maneuvered for engaging with a recess in the wall of the rod. The drill bit is then introduced into a sheath in the boring sensor, which performs as a tubular guide routing the drill bit toward the predrilled hole at the distal end of the rod where it is turned laterally toward the bone and drilled from the inside through the cortical end and outwardly. This approach requires additional hardware components, manipulative steps and greater installation time and cost.
Accordingly, there is a need for an improved, more economic intramedullary rod and more efficient and simplified system for fixation of the rod to bone.